The purpose of this study was to determine whether stress, sleep disturbance, or fatigue at 22 to 26 weeks of gestation is related to the incidence of preterm labor and birth in military women. Data were collected prospectively by questionnaires measuring factors contributing to preterm labor and birth. Hours worked per week were ascertained by telephone until the participants delivered. Postpartum medical records were reviewed for pregnancy outcomes. There was a trend for preterm labor to be associated with lower perceived fatigue severity, low sleep disturbance, and more negative life events. Officer rank was related to both preterm labor and delivery. Findings indicate that the perception of fatigue may be protective against preterm birth and that military officer rank is a risk factor for preterm labor and birth.